SEOUL -(MarketWatch)- Energy-deficient South Korea and Japan are mulling the implications of U.S. moves to toughen sanctions against Iran, with each facing a potential disruption of oil imports from a country that meets close to 10% of their crude needs.

South Korean officials may meet with U.S. officials as early as this month to negotiate over the U.S. sanctions, a person with direct knowledge of the matter said in Seoul Wednesday, while an official with Japan's Ministry of Economy, Trade and Industry said dates for negotiations weren't known yet.

If the U.S. pushes ahead with its new sanctions, there are two ways South Korea could be excused from having to completely halt Iranian crude imports, said the official, who declined to be identified further.

One is to be considered an "exception" to the proposed law and the other would be to be granted a "waiver."

On Jan. 1, President Barack Obama signed sanctions against Iran's central bank into law, in a move that senior administration officials say could hit Iranian oil sales but will be implemented in a way that won't damage the global economy.

South Korea imported an average of 247,000 barrels a day of Iranian crude in January-November 2011, according to Korea National Oil Corp. while Japan's crude imports from Iran were around 314,000 barrels a day over the same period, finance ministry figures show.

South Korean Finance Minister Bahk Jae-wan said Wednesday that it won't be easy to reduce dependence on crude oil from Iran.

Japanese foreign minister Koichiro Gemba said he had told U.S. Secretary of State Hillary Clinton that the sanctions "could have negative effects on the global economy, including private consumption in the U.S."

"There are many questions to address with regards to such sanctions, including substitute suppliers of oil for Iran and whether it is possible to find ways to settle transactions other than through the Iranian central bank," Gemba told a press conference.

To be an exception, South Korea would have 180 days from the date the U.S. law took effect to reduce Iranian crude imports, while for a waiver it would have to act within a 120-day period in a way that would help reinforce U.S. security, the Seoul official said.

What needed clarification is "how much effort do we need to show in order to be either an exception [to the law] or to get a waiver," the person said.

In Tokyo Wednesday, a METI official noted that the U.S. sanctions law contained waiver provisions, but that doesn't mean they will automatically apply to Japan.

To be exempted from sanctions, apart from cutting oil imports from Iran, a country provides concrete assistance to the U.S. in dealing with Iran's nuclear program, the Japanese official said.

An import reduction is by no means a foregone conclusion, but certainly expects" it to be on the negotiating table with the U.S., he said.

Japan and the U.S. have been holding talks over Iran's nuclear program since the Security Council adopted a resolution against Iran in 2006, but what is different now is that oil imports have been put on the U.S. sanctions list for the first time. This could have far broader repercussions for the Japanese economy, he added.

For its part, the South Korean government sees the need for oil refiners to voluntarily demonstrate efforts to reduce crude imports from Iran during the next few months, the Seoul official said.

SK Innovation (096770.SE), South Korea's largest refiner and main buyer of Iranian oil, has yet to receive an official notice from the government on how to deal with Iran issues, a spokeswoman said, declining to elaborate on current term contracts with Iran on crude supplies.

Hyundai Oilbank, which imported 70,000 barrels of Iranian crude daily last year, has yet to decide on how much it will import from Iran in 2012, a company spokesman said, adding it will look into various measures, including a diversification of crude sourcing and an increase in dependency on spot purchases.

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